In general, the design and manufacture of a tire includes consideration of multiple factors such as e.g., tread wear, rolling resistance, traction, noise generation, and numerous others as well. Problems are encountered in attempting to optimize such factors because, conventionally, improvement of one factor may have a deleterious impact on one or more other factors. As such, typically a balance or compromise is selected.
For example, one common problem confronted in tire design and manufacture is how to lower the rolling resistance of the tire without compromising the wear life of the tread or its wet adherence performance. More specifically, in general the addition of circumferentially-oriented grooves provides volume for the receipt of water that can improve wet traction but can also have a negative impact on rolling resistance and/or tread wear because e.g., it reduces the rigidity of the tread and the effective volume of rubber of the tread. Conversely, the removal of such circumferentially-oriented grooves can increase rigidity to improve rolling resistance and/or tread wear but can also have a correspondingly negative impact on wet traction.
Prior approaches to this problem have included layering the tread design such that an additional circumferentially-oriented groove appears only after a certain amount of tread wear has occurred. For example, see U.S. Patent Application Publication No. 2011168311A to Voss et al. and U.S. Patent Application Publication No. 2010072523, which are commonly owned by the assignee(s) of the present application. These references, for example, provide that at the early stages of tread life, a circumferentially-oriented groove may be hidden and located between other circumferentially-oriented grooves that are not hidden. As the tread wears, the hidden circumferentially-oriented groove is uncovered with the removal of tread rubber and provides for assistance in wet traction. This design approach can also improve rolling resistance and wear life of the tread. However, for large tread widths especially, the distance between circumferentially-oriented grooves can affect wet traction. For example, increasing the distance between circumferentially-oriented grooves by providing a hidden circumferentially-oriented groove therebetween can lower the ability to uniformly dry the tire contact patch during use. This effect can become even more pronounced at higher speeds. Accordingly, in view of the problems in the art including those set forth above, there is a need for a tire tread that can have improved rolling resistance and/or improved tread wear life potential without compromising wet traction performance.